1. Field of Invention
This invention pertains to a substrate with a shielded delay line and to a method for making the same.
2. Description of the Prior Art
In various electronic circuits it is frequently desirable to provide a means or delaying certain signals for a predetermined length of time. For circuits operating at very high frequency, where the required delay is in the microsecond or sub-microsecond range, the delay means comprises a conductor having a preselected length. In order to reduce the overall size of the delay means the conductor is usually formed in the shape of an axially coiled spiral.
Usually the various electronic devices used in the electronic circuits are mounted on a printed circuit board. However it is fairly difficult to mount the above-mentioned delay coil on a circuit board because of its size and fragility. Frequently, the coil is encapsulated in a dielectric material to give it rigidity, however this process is expensive. Furthermore, at high frequency the conductor must be shielded to eliminate noise or extraneous signals. This shielding even further complicates the construction of the delay coil and the manner of mounting it to a printed circuit board.